Protein-capture reagents are indispensable for delineating the molecular mechanisms of diseases, to detect and characterize cellular abnormalities, and to characterize biological effects of drugs. However, the current paucity of high-quality protein-capture reagents presents a major bottleneck in virtually all areas of biomedical sciences. The overarching goal of this project is to develop an innovative and powerful protein-capture technology with high levels of fidelity and predictability. We aim to overcome a major limitation of currently available technologies where specificity and epitopes must be individually tested by laborious methods after generating protein-capture reagents. We introduce a new concept, C-clamping, that enables to direct capture reagents (C-clamps) exclusively to the C-terminal (6-8) residues of proteins with high fidelity and high affinity. C-clamps are in the form of robust recombinant binding proteins generated using state-of-the-art phage-display technologies. Virtually every protein has a unique C-terminal signature that can be recognized with high efficiency by C-clamps. The a priori knowledge of epitope location allows one to accurately predict the level of specificity by identifying potential cross-reactivity through database search and to implement strategies to eliminate off-targets. These attributes make C-clamps particularly suited as the core technology for generating a comprehensive set of protein capture reagents. Furthermore, C-clamping is ideally suited to detect proteolytic neo-epitopes generated by proteolysis, markers of biomedically important processes (e.g. apoptosis). Our proof-of-concept experiments have successfully demonstrated the feasibility and enormous potential of C-clamping. Proposed studies aim to establish C-clamping as a general technology by producing high-performance capture reagents for high-value targets including integral membrane proteins, splice variants, viral proteins and caspase neo-epitopes. C-clamping represents a paradigm shift in capture-reagent generation, and the establishment of C-clamping will make large contributions to the entire molecular biomedical sciences.